The present invention relates to a directional reflection screen and display system which enables an observer to obtain a stereoscopic view using a binocular parallax without wearing special glasses.
A display system which enables an observer to obtain a stereoscopic view using a binocular parallax without wearing special glasses uses a combination of image projecting means and a directional reflection or transmission screen. A directional reflection screen which uses a corner-shaped mirror sheet as horizontal focusing means for an observer is disclosed in, for example, xe2x80x9cTHREE-DIMENSIONAL IMAGE ENGINEERINGxe2x80x9d, (written by Yoshitaka Ohkoshi, published by Asakura Shoten), pp. 28 and 91-97. Such a directional reflection screen is illustrated in FIGS. 15 and 16.
The screen SO1, shown in FIG. 15, enables horizontal focusing by providing a corner-shaped mirror sheet 10R having right angles at the peaks and valleys, and vertical diffusion by providing a mirror surface 11 having appropriate unevenness, where the unevenness may resemble a sinusoidal curve. The screen S02, shown in FIG. 16, enables vertical diffusion by providing a surface 21 with a lens effect on corner-shaped mirror sheet 10R.
As shown in FIG. 17, in either of these conventional corner-shaped mirror sheets 10R of FIGS. 15 and 16, rays 41i and 42i which are incident on mirror surfaces 11i are respectively reflected in the same horizontal direction that the incident rays come from as reflected rays 41r and 42r. Accordingly, a picture signal, which is emitted from an image projecting apparatus such as a liquid crystal projector and is projected on the screen shown in FIG. 15 or 16, is reflected and focused on the position of the image projecting apparatus in a horizontal direction. Specifically, as shown in FIG. 18, image projecting means 50, which includes, a right-eye projector 50R and a left-eye projector 50L, is disposed immediately above or below a right eye 60R and a left eye 60L of an observer 60. A pair of picture signals which form a stereoscopic image signal, based on a binocular parallax effect, are projected on a directional reflection screen S00 which is similar to screen S01 of FIG. 15, whereby the observer 60 can observe a stereoscopic picture.
However, such a directional reflection screen for the above-described prior art stereoscopic display has only one focus point in a horizontal direction. Thus, a plurality of observers cannot simultaneously observe a stereoscopic image without an observation platform which enables the observers to overlap each other in a vertical direction.
An object of the present invention is to provide a stereoscopic display system which overcomes the above-mentioned problem as well as other problems of the prior art and allows a plurality of observers to simultaneously observe a stereoscopic image without wearing special glasses and without having to be vertically positioned with respect to each other as required by the prior art.
To solve the problems of the prior art, the present invention provides a display system having image projecting means and a directional reflection screen. The directional reflection screen includes horizontal focusing means for an observer. Horizontal focusing is enabled by a mirror sheet shaped to have a plurality of triangularly-shaped ridges that have included angles, at least some of which are non-right angles. Such a mirror sheet is referred to herein as a triangularly-shaped mirror sheet.
The present invention provides a directional reflection screen with a triangularly-shaped mirror sheet in which the included angles which are the non-right angles include a plurality of different included angles.
The present invention provides a directional reflection screen in which the plurality of different included angles are cyclically arranged.
The present invention provides a directional reflection screen that is concave in a direction which is at approximately right angles to a ridgeline of ridges of the triangularly-shaped mirror sheet.
Still further particulars of the present invention are set forth below.
A directional reflection screen is provided in which a base of the triangularly-shaped mirror sheet is formed of a polymer material.
A directional reflection screen in provided that includes a first portion for effecting focusing in a direction which is at approximately right angles to the ridgeline of the triangularly-shaped mirror sheet, and a second portion for effecting diffusion in a direction of the ridgeline of the triangularly-shaped mirror sheet.
A directional reflection screen in provided in which the first and second portions of the directional reflection screen are made from independent bases.
A directional reflection screen is provided in which the second portion for effecting diffusion in the direction of the ridgeline of the triangularly-shaped mirror sheet is made from a lens sheet.
A directional reflection screen is provided in which the base of the triangularly-shaped mirror sheet of the first portion of the screen and the base of the lens sheet of the second portion are formed of transmissive polymer materials. The first portion has a triangularly-shaped mirror sheet structure formed on one side and a flat surface formed on the other side. The second portion has a lens sheet structure formed on one side and a flat surface formed on the other side.
A directional reflection screen is provided in which the triangularly-shaped mirror sheet and the lens sheet are formed on outside surfaces of the respective first and second portions by opposing the flat surfaces of the first and second portions to each other.
A directional reflection screen is provided in which a focus of the lens sheet of the second portion of the screen is set at a location other than a mirror surface of the triangularly-shaped mirror sheet of the first portion.
A directional reflection screen is provided in which refractive indices of the polymer materials which respectively form the first and second portions of the screen are approximately equal to each other.
A directional reflection screen is provided in which a transmissive third portion which is approximately equal in refractive index to the polymer material which forms the second portion is inserted between the first portion and the second portion of the screen.
A directional reflection screen is provided in which a material which bonds together the first portion and the second or third portion of the screen has an approximately equal refractive index.
A directional reflection screen is provided in which the directional reflection screen is concave in a direction which is at approximately right angles to the ridgeline of the triangularly-shaped mirror sheet which constitutes the directional reflection screen.
A display system is provided having any of the above-described directional reflection screens and image projecting means.
The display system is such that all different included angle components of the triangularly-shaped mirror sheet are contained in one pixel which constitutes an image signal.
The display system is such that the polymer material which forms the base of the triangularly-shaped mirror sheet is transmissive, and the base has a triangularly-shaped mirror sheet structure formed on one side and a flat surface formed on the other side, an image signal entering the base through the flat surface.
The display system is such that a repetition length of a pixel in a horizontal direction relative to a triangularly-shaped mirror of the image projecting means is an integer times a repetition length of the triangularly-shaped mirror sheet.
The display system is such that a repetition length of a pixel in a vertical direction relative to the triangularly-shaped mirror of the image projecting means is an integer times the repetition length of the lens sheet.
The display system is such that an image of the image projecting means is formed by a matrix-addressed display.
The image projecting means independently project images to be respectively made incident on the left and right eyes of an observer, the images including a binocular parallax so that the observer recognizes a stereoscopic image.
The display system is such that the ridgeline of the triangularly-shaped mirror sheet which constitutes the directional reflection screen is at right angles to the observer.
These and other objects, features and advantages of the present invention will become more apparent in view of the following detailed description of the preferred embodiments in connection with the drawings.